Method for simultaneously determining total calcium, sulfate calcium and calcium sulfite in desulfurized fly ash

Abstract

The invention discloses a method for simultaneously determining total calcium, sulfate calcium and calcium sulfite in desulfurized fly ash. The method comprises the following steps: decomposing the calcium sulfite to lead calcium sulfite radical to be volatilized out in sulfur dioxide by acid; precipitating barium sulfate; determining the calcium sulfate by an indirect titration method; oxidizing the calcium sulfite into the calcium sulfate; precipitating the total sulfate radical; and realizing the calcium sulfite determination by difference reduction of the total sulfate radical and the sulfate radical. With the adoption of the method, the interference of substances such as calcium hydroxide and calcium chloride is eliminated; the barium sulfate is precipitated and needs not to be filtered; after the acidity is adjusted, the direct titration can be carried out; the method is simple and rapid to operate; titration is carried out by a potential titrimeter; and the simultaneous determination of the total calcium, the sulfate calcium and the calcium sulfite is realized. With the adoption of the method, the defect that an iodine method is not suitable for determining the calcium sulfite in the desulfurized fly ash is greatly overcome, and meanwhile, the content of the total calcium can be determined, so that the condition that the total calcium, the sulfate calcium and the calcium sulfite in the desulfurized fly ash at each stage in a metallurgy sintering smoke gas dry method and semi drying method desulfurizing process can be accurately determined is realized; and the simultaneous determination method is shortened for 3-5 times compared with the method for determining three components respectively.

Description

technical field [0001] The invention belongs to the field of metallurgical analytical chemistry, and relates to a method for joint determination of total calcium, calcium sulfate and calcium sulfite in desulfurization ash, in particular to a method for jointly determining total calcium, calcium sulfate and calcium sulfite in desulfurization ash by using a potentiometric titrator Calcium chemical phase analysis method. Background technique [0002] Because the content of calcium sulfite in desulfurization ash is much higher than that of wet desulfurization by-product - desulfurization gypsum, the detection method of desulfurization gypsum is not suitable for desulfurization ash. At present, the domestic detection of gypsum is generally based on the "GB / T 5484-2000 Gypsum Chemical Analysis Method" to determine the content of sulfur trioxide and calcium oxide. Among them, the determination of sulfur trioxide is the barium sulfate gravimetric method. The total amount of calcium...

AI Technical Summary

Problems solved by technology

This method is not suitable for desulfurization ash samples with complex components, because some desulfurization ash samples contain acidic substances such as chlorides, which are easily distilled out and react with alkaline solutions to make the determination of calcium sulfite higher; A test method for sulfate content in desulfurized gypsum (patent application number: CN200910075181.3)", which uses heating and drying at 350-370°C to remove crystal water, and converts crystal water into calcium sulfate dihydrate as sulfate content. Calcium sulfite is not considered, and it is not suitable for the determination of sulfate in desulfurization ash; the patent "Test method for sulfate content in flue gas desulfurization system (patent application number: CN200910073876.8)" is to oxidize calcium sulfite first, then use The gravimetric method is used to determine the total amount of sulfate, and then the iodometric method is used to determine the amount of calcium sulfite. Because the gravimetric method is cumbersome to operate, the cycle is long, and the iodometric method interferes seriously, it is not suitable for the determination of desulfurization ash.

[0003] The above-mentioned documents measure total calcium and all are to adopt artificial naked eye to judge the titration end point, be subject to the influence of operator's operation level easily; The gravimetric method operation of measuring calcium sulfate is loaded down with trivial details, the cycle is long; The iodometric method of measuring calcium sulfite is interfered by calcium hydroxide, The distillation method is interfered by chloride, so each method is not suitable for the determination of total calcium, calcium sulfate and calcium sulfite in desulfurization ash

Images